In rotary printing presses and other printing machines it is desirable to provide means engageable with an edge of the printing plate for securing same, by clamping, to the rotary printing drum or another portion of the press. It has already been proposed to provide such clamping means for actuation by an eccentric shaft.
In prior art systems for securing the printing plate on a printing machine, use has been made of so-called "quick-acting fastening bars" which can include a base to which a clamping bar is fixed by screws. The fastening screws permit a given swingability of the clamping bar with respect to the base, actuated by rotation of an eccentric shaft between the engaged and disengaged (locking and release) portions. The disadvantage of this conventional quick acting clamp arrangement is that it is effective only when the printing plate is of uniform thickness along the clamped edge or when it is adjusted accurately to compensate for varying thicknesses therealong. In the event such adjustment is imprecise or the printing plate has nonuniform thickness along the edge to be clamped, which is a common occurrence, the printing plate is not held firmly all along the clamped edge and a nonuniform stress is applied to the printing plate or the latter is held too loosely.